This invention relates to apparatus for cutting off successive lengths from continuously moving stock and more particularly to flying saws for severing rapidly moving tubing, pipe, rod or the like into accurately cut lengths as the material emerges from a mill. The apparatus described herein is designed particularly for sawing welded pipe into lengths, but it is understood that the invention has other uses and applications.
In the manufacture of steel pipe by a well-known process, skelp is heated to welding temperature in a furnace and then passed at high speed through forming and welding rolls in which the skelp is formed into tubular shape and the abutting edges welded together to form the pipe. The skelp is supplied in large coils and the forward end of one coil is welded to the trailing end of the preceding coil before the skelp enters the furnace, thus making it possible to carry on the welding operation for relatively long periods of time without interruption. Mills of this type operate at high rates of speed, such as 1,000 feet per minute or greater. In order to cut the pipe into lengths as it emerges from the mill, a high-speed flying cut-off mechanism is provided.
Flying saws or cut-offs for use in mills of this type are disclosed in U.S. Pat. No. 2,645,001 and in U.S. Pat. No. 2,775,808. In this type of apparatus a circular saw or other cutting tool is carried in a circular path or orbit by a rotary support, such as a crank mechanism. Means are provided for guiding the work in a horizontal path disposed in a plane parallel to the plane of the circular orbit of the cutting tool, the direction of action of the cutting tool being perpendicular to the path of the work. The work is guided in a path which is normally adjacent to, but which does not intersect, the circular path of the cutting tool; and means are provided for periodically deflecting the work upwardly from its normal path into the path of the cutting tool, thereby causing the stock to be severed. When cutting pipe of relatively large diameter, as disclosed in said Pat. No. 2,775,808, the superstructure upon which the rotary support for the saw assembly is mounted may be deflected downwardly at the same time that the work is deflected upwardly.
Apparatus of the type described above has been successfully used for many years and operates well at work speeds in excess of 1,000 feet per minute. Such apparatus is capable of uninterrupted operation for relatively long periods of time, can be adjusted to handle pipe of various sizes, can be operated at different mill speeds, and can provide high quality cuts at the ends of the pipe. Also the length of cut and the lineal speed of the cutting tool in its orbit can be varied while the apparatus is running. However, the efficiency of such apparatus has been limited at very high operational speeds for a number of reasons. The smoothness of operation and the quality of the cutting was reduced when the speeds were increased to 1500 feet per minute or higher. Another disadvantage of the apparatus was that malfunctions such as failure of the cut-off device necessitated shutting down the mill for a period of time.